Classification of E. coli

         

        E. coli is a rod-shaped, facultative anaerobic, gram-negative bacterium that consists of three layers: cytoplasmic, peptidoglycan, and lipopolysaccharide outer membrane in its envelope (Reshes et al., 2007) (refer to Fig. 1). Most E. coli strains live harmlessly in the large intestine flora (commensal strains). By producing vitamin K, vitamin B12, and preventing colonisation by pathogenic microbes, healthy E. coli positively impacts gut health (Martinson & Walk, 2020).

Pathogenic E. coli strains can cause different infections, as shown in Table 1. (Refer to Fig. 3)

 Table 1

Subtypes of Pathogenic E. Coli Strains 

Note: This table shows the subtypes of pathogenic E. coli, common diseases caused by those pathogens and the virulent factors that cause the host’s infection. Adapted from Allocati et al. (2013). Escherichia coli in Europe: An Overview, journal article.